5. Income Taxes (Details 1) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Deferred tax liabilities (assets):
Property, plant and equipment	$ 7,540	$ 6,787
Patents and goodwill	1,742	1,740
Benefit plans	(1,847)	(854)
Inventories	(367)	(282)
Capital loss carryover	(572)	(572)
Other	(418)	(116)
Deferred tax liabilities (assets)	6,078	6,703
Plus: Valuation allowance	609	609
Total deferred tax liabilities	$ 6,687	$ 7,312

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